Centrifugal compressor.



O. BANNER. GENTRIPUGAL COMPRESSOR. APPLIGATIQN FILED 00T. 25. 1912.

Patented Sept. 15, 1914.

15,1 leefe I IIIIII IIII INU

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P-NY., 0F JERSEY CITY, JERSEY, A CORPORATIN OF NEW'TEESEY.

CENTRIFUGAL GOMFRESSOLB.

. Specification. of Letters Patent.

Patented sept. is, rara.

pplicationl'ed October 25, 1912. Serie o. 727,650.

To aZ" 'wiom it may' concern Be it knownthat I, BAnNniaa subject of theGerman Emperor, resid-mg at Easton, in the county' of Northampton andState of Pennsylvania, have invented a certainnew and useful Improvement1n Cen.- trifugal Compressors, of which the following is a specication.

This invention-relates to centrifugal compressors and more particularlyto the regulation of such compressors.

When centrifugal compressors are designed for supplying differentvolumes of air or other fluid at a constant pressure their capacity canbe varied. within quite large limits simply byy re lating the motorbyordinary' speed governing means. There is a limit however to thisregulation since 1f the output ofthe compressor is decreased to lessthan' acertain p'ercentaggpl ofits full load (say 50 or 60% according tothe design) the compressor will 'pump, that 1s, 1n-

st'ead: of the air or gas flowing continuously through the compressor,it will build up pressure at certain points which will overcome the aircurrents coming through and forceA its Way back through the impellerscausing' a pulsation or pumping eiiect in the compressor.

Various means have been proposed for obviating this difficulty such forinstance as allowing suiiicient quantity of airto p ass through thecompressor to prevent pumping but permitting any excess over the amountdesired' in the load Vline t'o escape to the atmosphere. All thesemethods however result in the waste of the considerable power required;to force this excess air through the com ressor.

e object of the present invention is to provide means whereby aregulation below the pum ing limit can be eected and yet there W' l4 beonly a small' proportion of power wasted.

With this object in view I. have devised a compressor and a regulationmeans therefor, a practical embodiment of which is shown in theaccompanying drawings in which- Figure 1 is a side elevation partly insection of the compressor and the regulating means. Fig. 2 is ahorizontal section on the line 2-2 of Fig. l showing a detail oftheregulatingmeans.

In the drawings the compressor proper is shown as comprising a casing 1in which rotates a shaft 2 provided with a series oat `impellers 3 towhich air or other gas from the inletv 4 is successively passed and'- isdischarged into the exhaust pipe 5. Mounted on the shaft 2 is a turbinewheel 6 provided on its outer periphery with blades 7. This turbinewheel is adapted to be actuated under certain conditions by air or gastaken fromthe discharge pipe 5 through a pipe 8 and delivered lto theblades of the turbine wheel through nozzles 9, 10, 11, 12, 13 by aregulating mechanism which will now be described.

The air or gas passingfrom the discharge or" the compressor i's carriedthrough a measurin device, here shown, as a Venturi tube 14 o ordinaryconstruction which, as is Well known,` gives a difference in pressurebetween its throat 15 and its discharge opening 16 varying with theamount of air passing through it. From these points,nameiy the throat1'5 and the discharge opening 16; pipes 17 andl 1'8 respectively lead tothe vupper and lower ends of a cylinder 19 in whichl is reciprocallymounted a piston 20. A spring 21 tends to move the piston 2O in adownward direction and is ofsuch a strength that the position' of thepiston' varies with the difference of pressure in.a the ends of thecylinder caused by the difference in pressure in the throat anddischarge opening of the Venturi tube 14.

A rod 22 is secured at the lower side of the piston and operates througha connecting arm 23, a cam rod 24 on which is secured a series of cams25, 26, 27, 28, 29.

These cams co-act with plates 30, 31,32,33,\-

34- secured by rods 35, 36, 37, 38, 39 to valves 40, 41,42, 43, 44 whichare slidably mountedin the side of a valve chest 45 and controlrespectively the nozzles 9, 10, 11, 12, 13.- Springs 46, 47, 48, 49, 50surrounding the valve rods and engaging the plates 30,- 3 1-, 32, 33, 34tend to hold the valves in open position.l

In operation, regulation above the pumping limit is effected aspreviously stated by ordinary speed governing means. When the compressoris operating above this limit the diierence in pressure in the throat 15and= the discharge 16 of the Venturi tube 14 is such that the piston 2Ois held in its uppermostv position and the cams 25 to 29 areconsequently in such a position that the valves 40 to 44 are pressedinwardly closing the rio `nozzles 9 to 13 and lallowing noairto passthrough the pipe 8. The spring 21 however is of such a strength that assoon as the amount delivered by the compressor falls to the point wherepumping begins it will move t-he piston 2() downward', the dierence inVcourse will exert a rotative force on the shaft 2 and will relieve themotor driving the compressor of a certain amount of load. If the demandon the compressor falls still lower the piston 20 will move furtherdownward allowing valves 43, 42, 41, 40 to open successively, the numberopening depending upon the amount of air deman ed. In this way asuccessively greater amount of air will be withdrawn from the dischargepipe 5 and vpassed through the nozzles to the turbine wheel increasingthe amount of power developed by the wheel and relieving to aproportionate extent the load on the motor driving the compressor. Inthis way when the demand is low instead of a constant amount of powerbeing required below a certain limit by reason of the fact that allexcess over the demand below the pumping limit is wasted, the powerexpended will bear a ratio to the demand depending on the eflciency ofthe ,turbine wheel and will be accordingly reduced when the compressoris running under the pumping limit.

The arrangement as shown is only one of a number of modifications whichmight be devised. Any form of measuring device could. be substituted forthe Venturi tube -shown and any form of throttling mechanism whetherwith a plurality of nozzles or not, could be used instead of thearrangement shown.` Furthermore, the air turbine wheel may have anynumber of rows of blades or stages and may or may not be directlyconnectedwith the compressor shaft. It is ad- `vantageous however tohave the discharge gas-to a lower degree.

In Vsome cases, for instance in high pressure compressors, the expansionof the air mayreduce the temperature of the compressor to such an extentthat the circulation water would freeze. Under such conditions the airfrom the discharge may be heated to lthe desired extent by any suitablemeans,

such as a steam jacket 51 before being conveyed to the expansion nozzlesof the turbine wheel.

AIt is to be understood that the present showing and descriptiondiscloses onlyv one v specified-.modification of myinvention and.

other forms and modifications are included in the spirit and scope ofthe invention as pressor having a discharge line, a demand measuringdevice, an engine operated by compressed iiuid from said discharge line,and means controlled by saiddemand measuring device to supply fluid tosaid engine from said discharge linein an amount inversely proportionateto thevdemand.

. 2. In combination a centrifugal `com-` pressor having a dischargeline, a .demand measuring device, an engine ,operated by compressed iuidfrom said discharge line and operatively connected with saidcompressor,`and valve mechanism operated from said demand measuringdevice to supply fluid from said dischargeline to said engine in anamount inversely proportionate to the demand.

3.v In combination, a centrifugal compressor having a discharge line, ademand measuring device in said discharge line supplying two fluidpressures whose difference varies with the demand, an engine operated byfluid from said discharge line and operatively connected with saidcompressor, valve mechanism for controlling the ow of fluid from saiddischarge line to said engine, valve motor mechanism. for controllingsaid valve, and fluid connections for conveying the two pressures fromsaid demand meas-v uring device to said valve motor mechanism pressor,having a discharge line, a Venturi tube in said discharge line, anengine opl eratedv by -fluid from said discharge line, and operativelyconnected with said compressor, valve mechanism for controlling the iiowof fluid from said discharge line to said engine, a valve moto1comprising a cylinder and piston for operating said valve, and fluidpassages leading from the throat and discharge of said Venturi tube toopposite ends of said cylinder to move said motor piston as thedischarge through said Venturi tube varies. i

5. In combination a centrifugal/f compressor Khaving a discharge line, ademand measuring device, jan engine operated by compressed fluid fromsaid discharge line, means controlled b said demand measuring device tosuppl said'discharge ine in an amountinversely I.proportionate to thedemand and means to uid to said engine from compressed fluid from saiddischarge line,

means controlled by said demand measuring device to supply Huid to saidengine from said discharge line when said demand falls below apredetermined minimum and means to heat said fluid before it is admittedto said engine.

7 In combination, a centrifugal compressor having a discharge line and ademand measuring device, an engine operated by compressed fluid fromsaid discharge line, and means controlled by saiddemand measuring deviceto convey fluidv to said engine from said discharge line when saidde'nand falls below a predetermined minimum.

8. In combination, a centrifugal compressor having a discharge line, ademand measuring device in said discharge line, an

l engine, a passage for conveying operating fluid from said dischargeline to said engine, a valve mechanism in s aid fluid passage forcontrolling the flow therethrough, and operative connections betweensaid valve mechanism and said demand measuring device to admit fluid tosaid engine when the demand falls below a predetermined minimum in anamount proportionate to the fall of the de- .mand below saidpredetermined minimum.

9. In combination, a centrifugal compressor having a discharge line andalde-v .mand measurlng device, an engine, means OTT@ BANNER.

Witnesses:

PAUL HOFFMAN, F. A. Porn.

